Granular water-soluble perborate-containing salt mixture



March 14, 1961 GRANULAR WATER- Filed May 4, 1956 J. SCHMIDT ETAL2,975,142

SOLUBLE PERBORATE-CONTAINING SALT MIXTURE 2 Sheets-Sheet 1 INVENTORJOACH/M SCHMIDT WERNER ME/NHOLD BY [3% W ATTORNEY:

March 14, sc MlDT ET GRANULAR WATER-SOLUBLE PERBORATE-CONTAINING SALTMIXTURE Filed May 4, 1956 2 Sheets-Sheet 2 4:. a INVENTOR JOACH/MSCHMIDT WERNER MEI/VHOLD ATTORNEYs GRANULAR WATER-SOLUBLE PERBORATE-CONTAINING SALT MIXTURE Joachim Schmidt and Werner Meinhold, Dusseldorf-Benrath, Germany, assignors to Henkel & Cie. G.m. b.I-I.,Dusseldorf-Holthausen, Germany, a corporation of Germany Filed May 4,1956, Ser. No. 582,885

Claims priority, application Germany June 11, 1955 11 Claims. (Cl.252186) This invention relates to granular, water-solubleperborate-containing salt mixtures.

Perborates are frequently used in detergents and bleaching agents asoxygen-liberating materials. Since perborates are temperature-sensitive,particularly in the presence of water, they must be mixed with thedetergents and bleaching agents after the liquid or paste has beenconverted into a powder by drying.

The commercially available borates generally are in solid, finelydivided form, having a relatively small particle size. Since theparticle size of the commercially available borate is frequently aboutone-tenth to onehundredth that of the other components of the detergent,the same would tend to separate out upon transportation and storage.

In order to overcome this difi'iculty, attempts have been made toproduce perborates of low bulk weight by heating the same on hotsurfaces. In this connection, however, the particles formed do not havethe necessary mechanical strength, and, unless the operation is verycarefully effected, there is a strong tendency of the perborates todecompose.

One object of this invention is the granulation of finely dividedperborates into a more coarsely granular form, which may be mixed withdetergents and bleaching agents without any tendency toward separation.

A further object of this invention is a novel, granular, perborate saltmixture, which may be used in the same manner as a conventionalperborate being mixed with detergent and bleaching agents without anytendency toward separation. These, and still further objects will becomeapparent from the following description, read in conjunction with thedrawings, in which:

Fig. 1 is a diagrammatic representation of a plant set-up for efiectingthe process in accordance with the invention;

Fig. 2a is a diagrammatic front elevation partly in section, showing anembodiment of a granulating device for use in accordance with theinvention;

Fig. 2b is a diagrammatic side elevation partially in section, showingthe granulating device of Fig. 2a;

Fig. 2c is a diagrammatic perspective view showing the granulatingdevice of Fig. 2a;

Fig. 3a is a diagrammatic side elevation partially in section, showing afurther embodiment of a granulating device for use in the process inaccordance with the invention; and

Fig. 3b is a diagrammatic front elevation showing the granulating deviceof Fig. 3a with a portion of the drum rim cut away.

In accordance with the invention, a novel, granular salt mixturecontaining a perborate, which may be used in the conventional manner indetergents and bleaching agents without any tendency toward separationis formed by moving a finely divided, water-soluble perborate, andpreferably sodium perborate, on a support surface for contact betweenthe individual divided particles, While 2,975,142 Patented Mar. 14, 1961spraying the perborate with an aqueous solution of an inorganic saltcapable of crystallizing with the binding of water of crystallization.The aqueous salt solution sprayed should contain an amount of water notsubstantially in excess of the amount of water capable of being bound aswater of crystallization by the salt mixture formed, and the contact ofthe perborate in the aqueous solution should be effected at atemperature allowing crystallization of the salt solution.

As a result of the process, a salt mixture forms, in which substantiallyall of the water sprayed is bound as water of crystallization, and inwhich a granular perborate salt mixture is formed, the granules of whichare composed of individual, finely divided water-soluble perborateparticles, such as sodium perborate particles bound together byinorganic salt crystals containing water of crystallization. Theperborate is present in the mixture in amount ranging from 15% by weighttrihydrate to 95% anhydride, as, for example, in the case of sodiumperborate in amount ranging from 15% NaBO .H O 3H O to 95% by weightNaBO .H O and preferably to 65% by weight of NaBO H O The perborate maybe admixed with a solid divided inorganic salt, such as the same saltused in the sprayed solution in calcined form prior to the spraying andthere may be present in the mixture, and/ or preferably in the solutionthe customary stabilizers for perborate compounds, such as magnesiumsilicate or other water insoluble silicates, magnesium soaps, magnesiumphosphates, metastannic acid, etc.

The finely divided perborate, when the same is sprayed, may be moved inany desired manner, so that the individual particles contact each otherto conglomerate, and may, for example, be sprayed in conventionalrotating granulation devices. The perborate particles, however, may notbe eddied or atomized in a gas stream such as air.

The perborate particles struck by the sprayed solution adhere to otherperborate particles which have preferably not been wetted by thesolution, and there is formed a granulate which consists of a pluralityof perborate particles of original size, which are bonded together bythe sprayed aqueous solution of inorganic salts. Since perborateparticles, in the preferred embodiment of the process, are at roomtemperature, while the solution is generally sprayed at highertemperature, the solution cools down and solidifies with the formationof the solid salts which contain water of crystallization. There is thusproduced a solid granulate of perborate particles of original size,which are cemented to each other, this granulate, upon being introducedinto water, rapidly breaking up into the original perborate particles,due to the dissolving of the layer of inorganic salts containing waterof crystallization located between or on the perborate particles, sothat the entire original surface of the perborate powder is offered thewater. Accordingly, these particles dissolve almost as rapidly as thenon-granulated perborates of the original size.

As starting material, there is used primarily sodium perborate of theformula:

not limited to the use of perborates of the indicated particle size.

Inorganic salts which take up water of crystallization uponcrystallizing are, for example, the carbonates and ortho-, pyroandpolyphosphates, as well as the sulfates of the alkalis, particularlysodium and potassium. Mixtures of different salts may also be employed,in which connection the mixtures may contain identical or differentcations and/or identical or different anions. It is advisable to userapidly crystallizing solutions of salts which give off little heat ofcrystallization upon crystallization. This, however, is not absolutelynecessary for the preparation of perborates of good solubility andstability, since the heat of crystallization which is liberated upon thesolidification of the spray solution can be removed by cooling theoriginally formed, still solidifying or just solidified granulates inany conventional manner. The quantity of water to be added in the formof a solution of inorganic salts should be such that the added water canbe bound by the inorganic salts present in the form of water ofcrystallization. If partially or completely dehydrated'perborates aregranulated, they also are to be included among the inorganic salts whichcan take up water of crystallization. The quantity of water in ratio tothe quantity of inorganic salts can vary within wide limits and can beso adjusted that the inorganic salts in the finished granulate arepresent between the lowest possible hydrate stage and the highestpossible hydrate stage. It has been found advisable to regulate thewater content in such a manner that the water-vapor partial-pressure ofthe finished granulates is not higher than the waterwaporpartial-pressure of Na CO .7H O. The regulation of the degree ofhydration of the inorganic salts used for the granulation is possiblenot only by the adjustment of a given concentration of the solution tobe sprayed, but may be effected by admixing these salts in calcined formto the perborate. Finally, the water content of the granulates obtainedcan be reduced by carefully drying them, for example, in a stream ofair.

The quantity of the spray solution of inorganic salts, the concentrationof which can lie between 10% by weight and the saturation concentrationat the temperature in question is dependent inter alia on the particlesize of the perborates to be granulated and the size of the desiredgranulates. This quantity decreases with an increase in the particlesize of the starting perborate and increases with the size of thedesired granulates. If it is merely desired to convert perborate powderinto granulates, then, in many cases, depending on the desired particlesize of the granules, such small quantities of solution will besufficient so that the granulate contains 95% and preferably 65% byweight NaBO .H O- the balance consisting of salt hydrate includingpossible stabilizers. Generally, more solution is employed, so that inthe granulate, in addition to NaBO .H O .3I-I O there are present 540%by Weight and preferably 20-30% by weight of salt hydrate. may be ofinterest to prepare salt mixtures of lower perborate content which areintended, for example, for mixing with other detergent components. Inthis case, the NaBO .H O .3H O content can drop to 15% by weight. Thequantity of solution which is sprayed onto the perborate or perboratesalt mixture to be granulated is, for example, in the range of 5-45, andpreferably -25% by weight referred to the granulate to be produced.

The temperature of the spray solution can have any desired value betweenroom temperature (about C.) and the boiling point of the solution undernormal pressure, but temperatures of more than 95 C. are seldom used.There are generally employed hot solutions-of inorganic salts of suchconcentration that upon cooling they precipitate solid salts or evenentirely solidify. For this reason, the storage tanks, the conduits, andthe nozzles should be heated. Furthermore, it is advisable In manycases, however, it

, between 5-200 seconds.

to work under such conditions of concentration and temperature that thetemperature variations within certain limits cannot lead to thedepositing of solid salts containing water of crystallization thusclogging in the apparatus.

It has already been mentioned that upon the solidification of theapplied aqueous solution, a greater or lesser amount of heat ofcrystallization is liberated. It may be desirable to still remove thisheat as far as possible, while it is being given off. In such cases thegranulate is cooled, the cooling possibly starting directly after theformation of the not yet entirely solidified granules.

For the carrying out of the method of the invention, there is used anapparatus which brings about a continuous change in surface of the saltto be granulated, which is contained therein, so that each particle isstruck at least once by a drop of the sprayed solution during the timethat it remains in the apparatus. The process is preferably carried outin rotating tubes, drums, or plates, .in which connection the axes ofrotation of the tubes or drums may be horizontal or inclined, and theplates themselves may be horizontal or inclined. The material to begranulated is charged into the apparatus and passes through the same.The salt solution is sprayed onto the moving perborate mass, the nozzleas far as possible being of such a nature that the atomized solution ofinorganic salts is distributed as uniformly as possible over a surfaceagainst which the moving perborate mass strikes. Furthermore, nozzleswhich send out a fanshaped jet have proven preferable. In thisconnection, the fan of atomized solution should preferably form a rightangle with the direction of motion of the material.

The apparatus can be provided with stationary or with co-rotatinginserts, which, however, 'should extend extensively in the direction ofmotion of the material to be granulated, so that as little friction aspossible with the material passing through takes place, the continuouspassage of the material is favored, and contact of already formedgranules with fresh or only partially granulated material is extensivelyavoided. Such inserts are, for example, worms, scraper plates, ordeflector plates located in the direction of motion of the materialalong which the material slides. By means of these inserts, the resultis obtained that the time of stay of each particle in the apparatus isas close as possible to the average time of stay of the entire material.The time of stay of the material can vary within wide limits, as, forexample, However, a time ofstay of 301-0O seconds has proven advisable.In this way there is obtained a gentle treatment of the primarilyformed, still deformable granules. In case of a longer time of stay,there takes place, to be sure, a formation of larger granules, but atthe same time, there must be expected an undesired deformation of thestill unhardened granules. For this reason, it is advisable either toadjust the operating conditions in such a manner that granules of thedesired size are formed in one operation, or else to subject an alreadygranulated material to repeated granulation processes only after it isalready solidified and preferably also cooled. Two or more consecutivegranulation processes, however, should in general only be employed whena different salt is sprayed onto the granules in each granulationprocess.

If a cooling of the granules is desired, this can be effected in allknown apparatus such as, for example,

' cooling towers, cooling drums, etc. Cooling in parallel flow orcounter-flow of the material conveyed or eddied in a stream of air hasproven particularly suitable. It is also possible to allow the materialwhich is to be cooled to trickle down in a vertical pipe or tower andblow cold air against it at a speed which is somewhat less than thevelocity of fall of the granules. in this way, the cooling of thegranules can be combined with an air sifting.

One apparatus for the carrying out of the process of J the invention isshown in Fig. 1. The perborate to be granulated is located in thestorage vessel 1 and passes via the flow regulating or metering device 2into the funnel 3, which conducts it to the granulating device 4, whichis represented here as an oblique rotating plate. The storage vessel 5contains a calcined salt, which may be used as an auxiliary agent in thegranulation, and which can be conducted via the metering device 6 intothe hopper 3, where it mixes with the perborate. The pressure vessel 7contains a preferably hot solution of the salt contained in the storagevessel 5 or of another salt which crystallizes combining with water ofcrystallization. The vessel 7 is placed under pressure by a gas via theconduit 8 and the reducing valve 9, so that the solution passes throughthe line 10, which can be provided with heating means ll to the nozzle12 and from there is sprayed onto the granulating plate or tray 4. Thegranulating plate 4, which is shown in greater detail in Figs. 2ac, willbe described later. The granulated material passes over the rim of theplate into the funnel 13 and from there into the pipeline 14 and thevessel 15. Air is forced into this vessel 15 by the fan 16 via theconduit 17 and the throttle valve 18. Part of this air flows in thepipeline 14 in counter-current to the granulate which has just beenformed at such a speed that the speed of fall of the granulate inconduit 14 is strongly reduced, the granulate at the same time beingcooled. The granulate falls-to the bottom in container 15 and isconducted at the lower funnel-shaped part of the vessel 15 through theremaining part of the air forced into said vessel into the down conduit19, which is connected with the lower part of the riser conduit 20.Through the lower open end of the riser conduit 20, air is drawn in fromthe fan 27 at such a rate that the entire perborate is raised throughthis riser conduit into the separator 21. The air leaves the separatorthrough the conduit 22 and passes to the cyclone 23,

where the fine, non-granulated or insufliciently granulated particlesentrained by the stream of air are separated and returned throughconduit 24 to the funnel 3. The stream of air is drawn 01f through fan27, the throttle valve 26 and the conduit 25 from the cyclone 23. Theperborate separated in the vessel 21 leaves the separator at its loweropening and falls onto the shaking screen 28; the material fallingthrough the shaking screen is the granulate of the desired particle sizeand is discharged through the conduit 29. The coarsely granular materialremaining on the screen 28 is carefully comminuted in the mill 30. Theconduit 31 conveys the material emerging from the mill under the vacuumprevailing in the separator 21 back into the separator, where the dustparticles are removed.

Figures 2a-2c show the granulating plate 4 of Fig. 1 in detail, and Fig.2a is a projection of the granulating device on a plane parallel to thegranulating plate 46. Fig. 2b shows the granulating device in sectionthrough a vertical plane coinciding with the axis of rotation of plate40, and Fig. 2c shows the apparatus in perspective.

Referring to Figs. 2a-2c, the granulation takes place on the inclinedrotatable granulating plate 4t) provided with a rim 52, which plate isdriven by a variable geared motor 41. The geared motor 41 rests on ablock 37 and is swingably supported, together with the latter on a base42 via a pin 43. A locking device 44 permits the fixing of the desiredangle of inclination. The material to be granulated is conducted via thehopper 3 and the charging pipe 46 to the plate 40, where it is movedover the surface of the plate by the rotation of the latter. The mainportion of the material to be granulated collects on the rim of theplate at a place which is a greater or lesser distance from the deepestpoint of the plate, depending on the quantity of the material and thevelocity of rotation of the plate, and forms there a mass 39, which iscontinuously rolled around. A part of the material is carried along atthe rim of the plate in the direction of motion and then falls back fromthe upper rim over the inclined plate to the lower rim of the plate. Thequantity of the material carried along in this manner and the width ofthe surface taken up by the material which falls back, can be regulatedby the speed of rotation and the inclination of the plate. Thebackwardfalling material trickles in the form of similar curves orparallel lines 47 back over the inclined plate, and combines with themass 39 located at the lower rim of the plate. In this way a continuouschange in the surface of the material to be granulated, located on theplate, is obtained.

Onto the material trickling down in accordance with the lines 47, thereis now directed the preferably fanshaped jet 48 of atomized solution,which is conducted to the nozzle 49 via a conduit 50, provided with theaccompanying heating coil 51. Insofar as a fan-shaped nozzle jet isused, it is advisable to adjust it in such a manner that the lines 47form right angles with the generatrix of the jet 48. The sprayedparticles now come into contact with the mass 39 of the material to begranulated and have an opportunity there to agglomerate with otherparticles of material. It may happen that sprayed granules stick to therim 52 of plate 40. These granules are scraped off from the plate rim 52by a stationary scraper 53, which is connected by the holding device 38with the bearing block 37 of the motor 41. The scraper 53 is developedas a guide plate, the shape of which is identical to the curve of fallof the outermost lines 47. As a result of this, material particles aredeflected without strong friction into the desired direction of motion.Behind the scraper 53, there is in this way produced a surface which isfree of material onto which the starting material to be granulatedfalls.

The shape of lines 47 is dependent, inter alia, on the particle size ofthe materials falling along these lines. Since the coarse granules havenarrower curves of fall, the granulates migrate, corresponding to theincreasing particle size, towards the left, out of the region of thenozzle jet 48, and, finally fall, following the arrows 54, into thehopper 55, where they are further Worked in the manner described above.

The granulation can also be effected in a rotating drum, which is shownin longitudinal section in Fig. 3a

and in cross-section in Fig. 3b. The material to be granulated isconducted via the hopper 60 and the pipe 61 into the drum 62. It ispartially raised there by the rotary motion of the drum and forms thecontinuously moving mass 58 in the latter. The stripper 64 prevents tooextensive a lifting of the material and a baking of the sprayedparticles on the wall of the drum. The solution used for the spraying isintroduced through the pipe 56 into the inside of the drum 62, and isconverted there by the nozzles 57 into the spray jets 63. The sprayingneed not be effected over the entire length of the pipe. If only thecentral region 66 of the pipe 62 is used for the spraying, there takesplace in the upper region 65, where the material enters, a mixing of thecomponents to be granulated, and in the lower region 67 of the pipe theparticles struck by the solution have an opportunity to bake togetherwith other particles of the mass 58 to be granulated. The granulatesemerge from the drum along the path shown by the arrow 68.

The following examples are given by way of illustration and notlimitation:

Example 1 For the carrying out of the process, there was employed anapparatus in accordance with Fig. l, which was provided with agranulating plate in accordance with Pigs. Za-Zc. 1,270 lag/hr. of a dryperborate, which contained about of the water of crystallizationcorresponding to the formula Na BO .H O .3H O and also 123 kg/hr. ofcalcined soda were conducted continuously onto the granulating plate,the size, inclination, and velocity of rotation of which were such thatthe average time of stay of the perborate was 30-40 seconds. 397 kg./hr.of a 30% soda solution of a temperature of about 50 C. were sprayed bymeans of a nozzle 49 onto the perborate-soda mixture whichrtrickled downalong the lines '47 over the plate. The spray jet was fan-shaped. Theline of contact of the fan on the plate surface was in this connectionpractically perpendicular to the flow lines 4-7 of the perborateparticles. About 500 m. /hr of air of a temperature of 15-25" C. waspassed in counter-current in conduit 14 to the granulate which trickleddown from the plate. The time of stay of the granulates in the conduitwas about seconds. The material passed together with a part of thestream of air from the fan fan 16 via the conduit 19 into the riser pipe20, in which the material was conducted upward With an air velocity ofabout 8-9 meters per second and a velocity of its own of 13 meters persecond. Afterthe separation of the finelypulverized portion (about 50kg./hr.) in the separator 21 and cyclone 23, which was returned to thehopper 3, and separation of the oversize kg./hr) inthe shaking screen 28(inside mesh width 2.5 mm.), there were obtained at the screen outlet 291,790 kg./hr. of a granulate of the composition:

Percent by weight NaBO .H O 46.2

(=71% by weight NaBO .H O .3I-I O) Na CO Water of crystallization 40.3

The screen analyses of the starting materials and of the granulate areset forth in the table after Example 2.

Example 2 In the apparatus according to Example 1, 840 kg./hr. of theperborate used in the said example, and 101 kg. of calcined soda weresprayed with 179 kg./hr. of soda solution of a temperature of about C.The granulate was cooled in the pipe by conducting about 400 m. /hr. ofair at a temperature of 1S25 C. in counter-current to it. The time ofstay of the material in the tube 14- was about 7 seconds. The airvelocity prevailing in the riser 20 was about 7-8 m./sec., and thevelocity of the material itself 1-2 m./sec. In the cyclone 23, therewere obtained kg./hr. of fine materials, which were conducted to thehopper 3. From the shaking screen 28, there emerged 1,120 kg./hr. ofgranulate of the following composition:

Percent by weight Perborate (=75% by weight NaBO .H O .3H O) 48.7 Soda11.5 Water of crystallization 39.8

The screen analyses of the starting materials and of the granulates arethe following:

Percentage of Fractions in Weight Percent Mesh Aperture of the The sizeof the granulates to be produced in accord- A dry granular detergent ismade by spraying an aqueous paste of the said detergent in hot air. Thescreen analysis of the detergent is the following:

Percentage of Mesh aperture of the screen in mm. the fractions in Weightpercent parts by weight of this granular detergent are mixed with 20parts by weight of a granular perborate obtained according to theExamples 1 or 2. The mixture does not separate in handlingtransportation and storage as it does when the perborate is used in thenot agglomerated state.

The chemical composition of the detergent obtained by spraying was thefollowing one:

Percent by weight Water up to by weight.

As avoiding of separation is a matter of grain size and not of chemicalcomposition, detergents of any chemical composition may be used insteadof the above.

If the granular perborates should contain stabilizing agents theseshould be present in an amount of 05-20 percent by weight, calculated onthe Na BO .H O present in the salt mixture.

While the invention has been described in detail with reference to thespecific embodiments shown, various changes and modifications willbecome apparent to the skilled artisan, which fall within the spirit ofthe invention and the scope of the appended claims.

We claim:

' 1. Process for the production of granular salt mixtures containingperborates, which comprises moving a finely divided, water-solubleperborate on a support surface for contact between the individualdivided particles, while spraying the perborate with an aqueous solutionof an inorganic salt capable of crystallizing with the binding of waterof crystallization, said solution being unsaturated with respect to saidinorganic salt at the temperature of operation, the contact of theperborate and aqueous salt solution being effected 'at a temperatureallowing crystallization of the salt solution and agglomeration betweenindividual divided perborate particles, said salt solution sprayedcontaining an amount of water not substantially in excess of the amountof water capable of being bound as water of crystallization by the salt'mixture formed the quantity of solution which is sprayed onto theperborate to be granulated being in the range of 545% by weight based onthe granulate to be produced, and recovering the granular agglomeratedperborate particle salt mixture formed containing substantially all ofthe water sprayed as water of crystallization.

2. Process according to claim 1, in which said aqueous salt solution isa salt solution of a. member selected from the group consisting ofalkali metal carbonates, phosphates, sulfates, and mixtures thereof.

3. Process according to claim 1, which includes cooling the mixtureafter said spraying.

4. Process according to claim 1, in which said aqueous salt solutionsprayed contains a quantity of water not in excess of the amount capableof producing a salt mixture 9 with a vapor pressure equivalent to thevapor pressure of Na2CO3-7H20.

5. Process according to claim 1, in which said finely divided perborateis sprayed while being rotated in a totating granulating device.

6. Process according to claim 1, in which said perborate is admixed witha solid, divided, inorganic salt prior to said spraying.

7. Process according to claim 1, in which said perborate is a sodiumperborate.

8. Process according to claim 1, in which said spraying is effected inthe presence of a stabilizer for the perborate.

9. Process according to claim 1, in which the quantity of solution whichis sprayed onto the perborate to be granulated is in the range of 10-25%by weight based on the granulate to be produced.

10 10. Process according to claim 6, in which said solid, divided,inorganic salt is the same salt as the salt form ing said aqueous saltsolution.

11. Process according to claim 10, in which said solid,

divided, inorganic salt is a calcined salt.

References Cited in the file of this patent UNITED STATES PATENTS1,989,759 Longue et a1. Feb. 5, 1935 2,767,146 Bonewitz et al Oct. 16,1936 2,308,992 Mertens Jan. 19, 1943 2,524,394 Madorsky Oct. 3, 19502,706,178 Young Apr. 12, 1955 2,763,618 Hendrix Sept. 18, 1956 2,765,239Siegrist Oct. 2, 1956 UNITED STATES PATENT OFFICE CERTIFICATION OICORRECTION Patent No. 2,975,142 March 14', "1961' Joachim Schmidt et al.

It is hereby certified that error appears in the above numbered patentrequiring correction and that the said Letters Patent should read ascorrected below.

Column 3, line 44, for "perborates" read perborate column 6, line 75,the formula should appear as shown below instead of as in the patent:

NaBO ,H O .3H O

column 8, line 38, the formula should appear as shown below instead ofas in the patent:

NaBO .H O

Signed and sealed this 1st day of August 1961 (SEAL) Attest:

ERNEST W0 SWIDER DAVID Lo LADD Attesting Officer Commissioner of PatentsUNITED STATES PATENT OFFICE CERTIFICATION OF CORRECTION Patent No.2,975,142 March 14, 1961 Joachim Schmidt et a1.

It is hereby certified that error appears in the above numbered patentrequiring correction and that the said Letters Patent should read ascorrected below.

Column 3, line 44, for "perborates" read perborate column 6, line 75,the formula should appear as shown below instead of as in the patent:

column 8, line 38, the formula should appear as shown below instead ofas in the patent:

NaBO II-I O Signed and sealed this 1st day of August 1961.

(SEAL) Attest:

DAVID Lo LADD Attesting Officer

1. PROCESS FOR THE PRODUCTION OF GRANULAR SALT MIXTURES CONTAININGPERBORATES, WHICH COMPRISES MOVING A FINELY DIVIDED, WATER-SOLUBLEPERBORATE ON A SUPPORT SURFACE FOR CONTACT BETWEEN THE INDIVIDUALDIVIDED PARTICLES, WHILE SPRAYING THE PERBORATE WITH AN AQUEOUS SOLUTIONOF AN INORGANIC SALT CAPABLE OF CRYSTALLIZING WITH THE BINDING OF WATEROF CRYSTALLIZATION, SAID SOLUTION BEING UNSATURATED WITH RESPECT TO SAIDINORGANIC SALT AT THE TEMPERATURE OF OPERATION, THE CONTACT OF THEPERBORATE AND AQUEOUS SALT SOLUTION BEING EFFECTED AT A TEMPERATUREALLOWING CRYSTALLIZATION OF THE SALT SOLUTION AND AGGLOMERATION BETWEENINDIVIDUAL DIVIDED PERBORATE PARTICLES, SAID SALT SOLUTION SPRAYEDCONTAINING AN AMOUNT OF WATER NOT SUBSTANTIALLY IN EXCESS OF THE AMOUNTOF WATER CAPABLE OF BEING BOUND AS WATER OF CRYSTALLIZATION BY THE SALTMIXTURE FORMED THE QUANTITY OF SOLUTION WHICH IS SPRAYED ONTO THEPERBORATE TO BE GRANULATED BEING THE RANGE OF 5-45% BY WEIGHT BASED ONTHE GRANULATE TO BE PRODUCED, AND RECOVERING THE GRANULAR AGGLOMETRATEDPERBORATE PARTICLE SALT MIXTURE FORMED CONTAINING SUBSTANTIALLY ALL OFTHE WATER SPRAYED AS WATER OF CRYSTALLIZATION.